Do they actually work?
The point is to hold your air in the body than it is letting it out fast and hard. It is a perfect exercise. When I have done the lip trills and then sing a high note, the air stays constant. Practising the lip trills can help us do the entire range without changing your airflow. Try arpeggio breath low in the belly.
Exercise:
8-5-3-1
We don’t blast your air as a singer. We learn to coordinate the notes changing without the breath changing, i.e., singing high notes doesn't mean more airflow.